I am getting 60 degrees in movement either direction of true south. My south sat is 87. I can get down to 30 with no problem. You most likely are not lined up on your true south sat correctly. Tell USALS to go to 121 and peak the dish. Now get the thing tracking the arc properly and getting down to 72 should be no problem at all. Might even get Amazonas but that will be at the extreme limit of travel.
The number
Sadoun quoted you is most likely the end of safe travel so it is totally up to you to press farther than he says. He is far more knowledgable at this than I am
I get the same travel out of my
SG2100 so I consider both motors basically equal.